Molecular and cellular mechanisms of pancreatic injury

Vitamin B6 ameliorates acute pancreatitis by suppressing the caspase3 signaling pathway

BACKGROUND

Acute pancreatitis (AP) is a prevalent exocrine inflammatory disorder of the pancreas characterized by pancreatic inflammation and injury to acinar cells. Vitamin B6 (VB6) is a vital nutrient that plays a significant role in preserving human health and has anti-inflammatory and anti-apoptotic effects.

METHODS

This study aimed to explore the potential pancreatic protective effects of VB6 in mitigating pancreatic inflammation and apoptosis induced by taurocholate sodium (TLCS) in an AP model and to assess the underlying mechanism of action. AP was induced in Sprague‒Dawley (SD) rats through TLCS administration and lipopolysaccharide (LPS)-treated AR42J cells, followed by treatment with VB6.

RESULTS

Various parameters associated with AP were assessed in both plasma and pancreatic tissues. VB6 has been shown to ameliorate the severity of AP through various mechanisms. It effectively reduces the levels of serum amylase, lipase, and inflammatory factors, thereby mitigating histological injury to the pancreas. Moreover, VB6 inhibited pancreatic apoptosis by downregulating bax expression and up-regulating Bcl2 expression in TLCS-treated rats. Additionally, VB6 suppressed the expression of caspase3. The anti-inflammatory and anti-apoptotic effects of VB6 observed in LPS-treated AR42J cells are consistent with those observed in a rat model of AP.

CONCLUSIONS

These results suggest that VB6 exerts anti-inflammatory and anti-apoptotic effects through inhibition of the caspase3 signaling pathway and has a protective effect against AP.

TMAO promotes apoptosis and oxidative stress of pancreatic acinar cells by mediating IRE1α-XBP-1 pathway

BACKGROUND

Acute pancreatitis caused by hyperlipidemia is a severe life-threatening condition. Therefore, it is urgent to develop new therapeutic methods to treat this disease.

METHODS

Cell viability was determined by the Cell Counting Kit-8 (CCK-8) assay. Western blotting (WB) was used to detect the expression levels of apoptotic and endoribonuclease inositol-requiring enzyme 1α (IRE1α)/X-box binding protein 1 (XBP-1) pathway-associated proteins. The induction of cell apoptosis was determined using flow cytometry. The expression levels of the oxidative stress indicators were measured by an enzyme-linked immunosorbent assay.

RESULTS

WB analysis and the CCK-8 assay demonstrated that trimethylamine-N-oxide (TMAO) decreased cell viability and facilitated apoptosis of MPC-83 cells in a dose-dependent manner. Furthermore, the induction of oxidative stress was assessed by evaluating the levels of specific markers, including hydrogen peroxide, reactive oxygen species, nitric oxide, and superoxide dismutase. The levels of the aforementioned markers were increased in the TMAO-treated group. Subsequently, the IRE1α/XBP-1 pathway-associated proteins were analyzed by WB analysis and the data demonstrated that the regulatory effects of TMAO on MPC-83 cells were meditated by the IRE1α/XBP-1 signaling pathway. Subsequently, rescue experiments were performed to further assess the effects of TMAO.

CONCLUSION

The present study provides evidence on the application of TMAO as a potential diagnostic and therapeutic strategy for the therapeutic intervention of hyperlipidemic acute pancreatitis.

Gut-lymph-lung pathway mediates sepsis-induced acute lung injury

This review attempts to unveil the possible mechanisms underlying how gut lymph affects lung and further gives rise to acute respiratory distress syndrome, as well as potential interventional targets under the condition of ischemia-reperfusion injury. We searched electronic databases including PubMed, MEDLINE, Cochrane Central Register of Controlled Trials, Google Scholar, Web of Science, and Embase to identify relevant literatures published up to December 2019. We enrolled the literatures including the Mesh Terms of “gut lymph or intestinal lymph and acute lung injury or acute respiratory distress syndrome.” Gut is considered to be the origin of systemic inflammation and the engine of multiple organ distress syndrome in the field of critical care medicine, whereas gut lymph plays a pivotal role in initiation of ischemia-reperfusion injury-induced acute respiratory distress syndrome. In fact, in the having been established pathologic model of sepsis leading to multiple organ dysfunction named by Gut Lymph theory, a variety of literatures showed the position and role of changes in gut lymph components in the initiation of systemic inflammatory response, which allows us to screen out potential intervention targets to pave the way for future clinic and basic research.

Chaiqin chengqi decoction alleviates severe acute pancreatitis associated acute kidney injury by inhibiting endoplasmic reticulum stress and subsequent apoptosis

BACKGROUND

Acute kidney injury (AKI), characterized by an increase of serum creatinine and urea, is a severe complication of severe acute pancreatitis (SAP) with high mortality. Endoplasmic reticulum (ER) stress has been considered as a key pathologic process in AKI. Chaiqin chengqi decoction (CQCQD) is an effective Chinese medicine formula for SAP treatment in China and has been used for many years. Our goal is to explore the role of CQCQD on ER stress of AKI in experimental SAP.

MATERIALS & METHODS

SAP was induced in rats by retrograde duct injection of 5% sodium taurocholate (NaTC, 1 ml/kg), sham operation (SO) rats simultaneously received saline infusion. Intraperitoneal injection of 4-PBA (50 mg/kg, once a day for three days before the surgery) or intragastric gavage of CQCQD (1 g/kg, 2 hourly × 3 after disease induction) was used to treat SAP rats. All animals were humanely sacrificed 12 h after disease induction. Histopathology scores of kidney and pancreas; serum biochemical indices and kidney protein levels of ER stress and apoptosis markers were assessed. Tubular epithelial cell line (HK-2) was treated either with TNF-α (10 ng/ml) or IL-6 (10 ng/ml) for 12 h plus either 4-PBA (0.1 M) or CQCQD (1 mg/ml) for in vitro study. Cell viability and markers of ER stress and apoptosis were measured.

RESULTS

Ductal perfusion of NaTC caused significant increases in serum lipase, amylase and pancreatic histopathology (inflammatory cell infiltration, interstitial edema, and acinar cell necrosis). Kidney histopathology (tubular dilation, brush border loss, little tubular necrosis, and cast formation), serum creatine and urea levels were raised when compared with the SO group. Moreover, apoptotic cell death markers (caspase-9, cleaved-caspase-3, and TUNEL) and kidney ER stress proteins (BIP, IRE1-α, XBP1s, and CHOP) were elevated after NaTC administration. 4-PBA and CQCQD significantly alleviated histopathological changes of kidney and pancreas, inflammatory cytokines, biochemical markers of AKI, ER stress proteins and apoptotic cell death markers. They also protected HK-2 cells from injury of TNF-α and IL-6, and alleviated both ER stress and apoptosis proteins in vitro.

CONCLUSION

CQCQD may alleviate SAP-related AKI by inhibiting ER stress-related apoptosis.

Chronic Pancreatitis—Update on Pathophysiology and Therapeutic Approaches

Chronic pancreatitis is an inflammatory condition characterized by structural change within the pancreas, that leads to progressive and irreversible loss of functioning pancreatic parenchyma, exocrine/endocrine dysfunction and an increased risk of pancreatic ductal adenocarcinoma. Whilst hallmarks of advanced disease are readily identifiable on routine clinical imaging, concordance between structural changes within the pancreas and symptoms is poor, such that early diagnosis can be challenging. Traditionally, chronic pancreatitis has been managed with a ‘step-up’ approach of measures including analgesia, therapeutic endoscopy and surgery (in a select minority of patients). Accumulating evidence is emerging to challenge this approach: early surgical intervention may offer the opportunity to interrupt the disease process before irreversible sequelae become established. This article provides an overview of the pathophysiology underlying chronic pancreatitis together with a review of the current evidence to support established and novel therapeutic approaches to the disease.

Alcohol sedation in adult Drosophila is regulated by Cysteine proteinase-1 in cortex glia

Although numerous studies have demonstrated that neuronal mechanisms regulate alcohol-related behaviors, very few have investigated the direct role of glia in behavioral responses to alcohol. The results described here begin to fill this gap in the alcohol behavior and gliobiology fields. Since Drosophila exhibit conserved behavioral responses to alcohol and their CNS glia are similar to mammalian CNS glia, we used Drosophila to begin exploring the role of glia in alcohol behavior. We found that knockdown of Cysteine proteinase-1 (Cp1) in glia increased Drosophila alcohol sedation and that this effect was specific to cortex glia and adulthood. These data implicate Cp1 and cortex glia in alcohol-related behaviors. Cortex glia are functionally homologous to mammalian astrocytes and Cp1 is orthologous to mammalian Cathepsin L. Our studies raise the possibility that cathepsins may influence behavioral responses to alcohol in mammals via roles in astrocytes.

Elevated intracellular trypsin exacerbates acute pancreatitis and chronic pancreatitis in mice

Intra-acinar trypsinogen activation occurs in the earliest stages of pancreatitis and is believed to play important roles in pancreatitis pathogenesis. However, the exact role of intra-acinar trypsin activity in pancreatitis remains elusive. Here, we aimed to examine the specific effects of intra-acinar trypsin activity on the development of pancreatitis using a transgenic mouse model. This transgenic mouse model allowed for the conditional expression of a mutant trypsinogen that can be activated specifically inside pancreatic acinar cells. We found that expression of this active mutated trypsin had no significant effect on triggering spontaneous pancreatitis. Instead, several protective compensatory mechanisms, including SPINK1 and heat shock proteins, were upregulated. Notably, these transgenic mice developed much more severe acute pancreatitis, compared with control mice, when challenged with caerulein. Elevated tissue edema, serum amylase, inflammatory cell infiltration and acinar cell apoptosis were dramatically associated with increased trypsin activity. Furthermore, chronic pathological changes were observed in the pancreas of all transgenic mice, including inflammatory cell infiltration, parenchymal atrophy and cell loss, fibrosis, and fatty replacement. These changes were not observed in control mice treated with caerulein. The alterations in pancreata from transgenic mice mimicked the histological changes common to human chronic pancreatitis. Taken together, we provided in vivo evidence that increased intra-acinar activation of trypsinogen plays an important role in the initiation and progression of both acute and chronic pancreatitis. NEW & NOTEWORTHY Trypsinogen is activated early in pancreatitis. However, the roles of trypsin in the development of pancreatitis have not been fully addressed. Using a genetic approach, we showed trypsin activity is critical for the severity of both acute and chronic pancreatitis.

Inhibition of the dephosphorylation of eukaryotic initiation factor 2α ameliorates murine experimental pancreatitis

BACKGROUND

Endoplasmic reticulum (ER) stress in the pancreas is closely associated with the development of acute pancreatitis. However, the role of the protein kinase RNA-like ER kinase (PERK) in this disease is not fully understood. We investigated whether an inhibitor of the dephosphorylation of eukaryotic initiation factor 2α, salubrinal, could improve murine experimental pancreatitis through the amelioration of ER stress.

METHODS

Acute pancreatitis was induced by the intraperitoneal administration of cerulein (50 μg/kg) six times at 1-h intervals followed by lipopolysaccharide (10 mg/kg). Salubrinal was administered intraperitoneally immediately after lipopolysaccharide injection and 3 h later. Mice were sacrificed 24 h after the first injection of cerulein, and serum amylase and proinflammatory cytokines were measured. The severity of pancreatitis was evaluated histologically using a scoring system. The expression levels of ER stress-related proteins were evaluated by Western blotting.

RESULTS

The administration of salubrinal significantly attenuated the increase in serum amylase levels and improved histologically assessed pancreatitis. The serum levels of proinflammatory cytokines were significantly suppressed in salubrinal-treated mice, as was the expression of glucose-regulated protein 78, CCAAT/enhancer-binding protein homologous protein, and cleaved caspase-3.

CONCLUSIONS

The amelioration of ER stress through augmentation of the PERK-signaling pathway may be a therapeutic target for the treatment of acute pancreatitis.

Peptidylarginine deiminase and deiminated proteins are detected throughout early halibut ontogeny - Complement components C3 and C4 are post-translationally deiminated in halibut (Hippoglossus hippoglossus L.)

Post-translational protein deimination is mediated by peptidylarginine deiminases (PADs), which are calcium dependent enzymes conserved throughout phylogeny with physiological and pathophysiological roles. Protein deimination occurs via the conversion of protein arginine into citrulline, leading to structural and functional changes in target proteins. In a continuous series of early halibut development from 37 to 1050° d, PAD, total deiminated proteins and deiminated histone H3 showed variation in temporal and spatial detection in various organs including yolksac, muscle, skin, liver, brain, eye, spinal cord, chondrocytes, heart, intestines, kidney and pancreas throughout early ontogeny. For the first time in any species, deimination of complement components C3 and C4 is shown in halibut serum, indicating a novel mechanism of complement regulation in immune responses and homeostasis. Proteomic analysis of deiminated target proteins in halibut serum further identified complement components C5, C7, C8 C9 and C1 inhibitor, as well as various other immunogenic, metabolic, cytoskeletal and nuclear proteins. Post-translational deimination may facilitate protein moonlighting, an evolutionary conserved phenomenon, allowing one polypeptide chain to carry out various functions to meet functional requirements for diverse roles in immune defences and tissue remodelling.

Genistein protects against acute pancreatitis via activation of an apoptotic pathway mediated through endoplasmic reticulum stress in rats

Acute pancreatitis (AP) is a severe and frequently lethal disorder, but the precise mechanisms are not well understood and there is lack of effective drugs. Therefore, our study examined the in vivo intervention effects of genistein and elucidated its mechanism in acute experimental pancreatitis models. We used cerulein or taurocholate to induce acute pancreatitis (AP) in Sprague-Dawley rats with prior genistein treatment. Histological examination of the pancreas was performed and the expression of unfolded protein response (UPR) components and apoptotic mediators like caspase 12 and c-Jun N-terminal protein kinase (JNK) were measured. The amount of apoptosis in pancreatic acinar cells was also determined. Our studies found that the severity of cerulein- or taurocholate-induced AP was rescued by prior genistein treatment. Genistein stimulated the activation of multiple endoplasmic reticulum (ER) stress-related regulators like GRP78, PERK, eIF2α, and upregulated the expression of the apoptotic genes, caspase 12 and CHOP. Moreover, TUNEL assays showed that genistein treatment promoted acinar cell apoptosis. Taken together, we speculated that ER stress-associated apoptotic pathways in AP are induced by genistein, which showed cytoprotective capacity in the exocrine pancreas. These data suggest novel therapeutic strategies that employ genistein in the prevention of AP.

Atrial natriuretic peptide attenuates endoplasmic reticulum stress in experimental acute pancreatitis

Increasing evidence shows that the endoplasmic reticulum (ER) stress is an early event that injures pancreatic acinar cells and contributes to the pathogenesis of acute pancreatitis. In the present work we sought to establish whether atrial natriuretic peptide (ANP) alleviated ER stress in rats with cerulein-induced pancreatitis. The major components of the unfolded protein response (UPR) and their downstream effectors were assessed by immunoblotting or fluorimetry and the ultrastructure of ER evaluated by electron transmission microscopy. Cross-talk with autophagy was evaluated by beclin-1 expression. ANP reduced binding immunoglobulin protein (Bip) expression (UPR major controller) which under non-stress conditions keeps inactive the stress sensor proteins: protein kinase-like ER kinase (PERK), inositol-requiring enzyme-1 (IRE1) and activating transcription factor 6 (ATF6). Although ANP did not change PERK expression it decreased p-eIF2α and enhanced downstream effector CHOP, suggesting that ANP stimulates ER-dependent apoptosis. In accordance, ANP also decreased Bcl2 expression and enhanced proapoptotic proteins Bax and Bak. The atrial peptide enhanced ATF6 expression and although it did not affect IRE1/sXBP1 signaling, it increased caspase-2 activity, also involved in ER-dependent apoptosis. Furthermore, ANP decreased beclin-1 expression. The ultrastructure of the RE revealed decreased swelling and conserved ribosomes in the presence of ANP. Present findings support that ANP alleviates ER stress in acute pancreatitis by modulating the three branches of the UPR and stimulates ER-dependent apoptosis. Gaining insights into the modulation of ER stress may help to develop specific therapeutic strategies for acute pancreatitis and/or medical interventions at risk of its developing like endoscopic retrograde cholangiopancreatography.

Intravenous injection of post-hemorrhagic shock mesenteric lymph induces multiple organ injury in rats

Post-hemorrhagic shock mesenteric lymph (PHSML) has an important role in the multiple organ injuries caused by severe shock. The current study investigated whether intravenous injection of PHSML induces organ injury in normal rats. Following the establishment of hemorrhagic shock in donor rats (40±2 mmHg, 3 h), PHSML was drained during hypotension at 1-3 h and then injected to normal rats through the femoral vein within 30 min. The mean arterial pressure (MAP) was measured, and samples were obtained for analysis of histology and biochemical indices at 2.5 h post-PHSML administration. PHSML administration resulted in a significant decrease in MAP at the early and late stage of the experiment. Structural damage of the lung, kidney, heart and liver was also observed, and the levels of urea, creatinine, aspartate aminotransferase, total bile acid and creatine kinase MB isoenzyme were increased in the plasma. Additionally, PHSML injection significantly increased the levels of trypsin, tumor necrosis factor-α (TNF-α), intercellular adhesion molecule-1 and receptor of advanced glycation end-products in the plasma, malondialdehyde in the lung and myocardium, and TNF-α in the lung, kidney, myocardium and liver. Intravenous injection of PHSML induced multiple organ injury in normal rats via increases in trypsin activity, inflammatory factors and free radical production. The findings indicate that PHSML return is an important contributor to organ damage following hemorrhagic shock.

Melatonin attenuates the inflammatory response via inhibiting the C/EBP homologous protein-mediated pathway in taurocholate-induced acute pancreatitis

Acute pancreatitis (AP) is a serious disease characterized by the activation of trypsin, autodigestion, edemas, hemorrhages and necrosis. However, the mechanisms of regulating the apoptosis and inflammation of acinar cells in AP remain unclear. The endoplasmic reticulum (ER) stress‑related molecule, C/EBP homologous protein (CHOP), has pro‑-apoptotic and pro‑inflammatory properties, in addition to regulating ER stress responses. In the present study, a lentivirus‑mediated RNA interference (RNAi) approach was used to specifically knockdown the expression of CHOP in the pancreatic tissue of Sprague‑Dawley rats to investigate the potential role of CHOP during AP, which was induced by the retrograde injection of 5% taurocholate into the biliopancreatic duct of rats. Pre‑treatment with melatonin was further used to identify the potential anti‑inflammatory mechanisms in AP. Pancreatic tissues were procured for western blot analysis, histological examination, reverse transcription‑quantitative polymerase chain reaction and immunohistochemical staining. ER stress was rapidly activated in the early stage and increased over time in the rat AP model. However, the silencing of CHOP expression markedly inhibited apoptosis and ER stress, reducing the activation of nuclear factor‑κB and inflammation injury in AP. Melatonin also exhibited anti‑inflammatory and apoptotic effects, and significantly decreased the expression of CHOP. Thus, it can be concluded that the CHOP‑mediated pathway serves an important role in the development of AP, and that melatonin can reduce pancreatic damage via the inhibition of CHOP expression.

Melatonin Attenuates Endoplasmic Reticulum Stress in Acute Pancreatitis

OBJECTIVES

The objective of this study is to explore the effect of melatonin on endoplasmic reticulum stress in acute pancreatitis (AP) and the molecular mechanism.

METHODS

Acute pancreatitis was induced in vivo in Sprague-Dawley rats by the retrograde injection of 5% taurocholate into the biliopancreatic duct and in vitro by treating AR42J cells with cerulein (10 nmol/L) plus lipopolysaccharide (LPS) (10 mg/L). The rats and cells were treated with melatonin (50 mg/kg in rats and 0.5, 1, and 2 mmol/L in AR42J cells) 30 minutes before AP was induced. After 9 hours, the cells and rat pancreas tissue were collected for Western blot, reverse transcription polymerase chain reaction, histological examination, immunohistochemistry, and immunofluorescence analysis.

RESULTS

Inositol-requiring 1α (IRE1α)-mediated Jun N-terminal kinase (JNK)/nuclear factor-kappa B (NF-κB) pathway were activated early in AR42J cells and rat AP models. Melatonin significantly inhibited the expression of proinflammatory cytokines. Western blot and immunohistochemical results all indicated that melatonin regulated apoptosis-related protein expression. In addition, melatonin treatment resulted in significantly reduced pancreatic tissue injury, as revealed by histological changes and pathological scores. Furthermore, melatonin treatment significantly reduced the activation of IRE1α-mediated JNK/NF-κB pathway-related proteins.

CONCLUSIONS

These findings suggest that melatonin protects AR42J cells and Sprague-Dawley rats against AP-associated injury, probably through downregulation of IRE1α-mediated JNK/NF-κB pathways.

Effect of mode of acinar cell death on acute pancreatitis

Acinar cell death is the most important pathophysiological change in the early stage of acute pancreatitis, and it has been the emphasis of the research. The mode of acinar cell death includes apoptosis, necrosis, necroptosis, autophagy, and pyroptosis. Some scholars have shown that acinar cell death affects the outcome of acute pancreatitis. Therefore, studying the mode of acinar cell death has great value in the assessment of the severity of acute pancreatitis. Apoptosis can reduce inflammatory response, and necrosis aggravates inflammatory response. In recent years, research on the effect of necroptosis and pyroptosis on acute pancreatitis has been carried out. This article will review the effect of apoptosis, necrosis, necroptosis, and pyroptosis on acute pancreatitis.

Progress in research of pyroptosis of pancreatic acinar cells

Pyroptosis is a kind of programmed cell death mediated by caspases-1/4/5/11. Pancreatic acinar cell death is the major pathophysiological change in early acute pancreatitis (AP), which is an important factor determining its progression and prognosis. Different ways of cell death affect AP progression differently. At present, most scholars believe that the increased proportion of apoptotic cells can mitigate AP, while necrosis has an opposite effect. In our early study, we used electron microscope to observe the morphology of acinar cells and found that there are many cells consistent with the characteristics of pyroptosis. The expression of caspase-1 was analyzed via immunohistochemical staining in acinar cells in AP, which suggests that pyroptosis may play a role in acinar cell death and inflammation. In this review, we review the recent findings regarding the occurrence and modulation of pyroptosis by caspase-1 and inflammsome, and in particular, discuss the potential mechanism and clinical significance of pyroptosis in AP, with an aim to provide new clues to the clinical diagnosis and therapy of this disease.

Animal models of gastrointestinal and liver diseases. Animal models of acute and chronic pancreatitis

Animal models of pancreatitis are useful for elucidating the pathogenesis of pancreatitis and developing and testing novel interventions. In this review, we aim to summarize the most commonly used animal models, overview their pathophysiology, and discuss their strengths and limitations. We will also briefly describe common animal study procedures and refer readers to more detailed protocols in the literature. Although animal models include pigs, dogs, opossums, and other animals, we will mainly focus on rodent models because of their popularity. Autoimmune pancreatitis and genetically engineered animal models will be reviewed elsewhere.

Endoplasmic reticulum stress is activated in acute pancreatitis

Endoplasmic reticulum (ER) is one of the most important cell organelles in the body, regulating protein synthesis, folding and aggregation. Endoplasmic reticulum stress (ERS) is a particular subcellular pathological process involving an imbalance of homeostasis and ER disorder. In the early stage of ERS, cells show a protective unfolded protein response that changes the cellular transcriptional and translational programs to alleviate the process. Therefore, a certain degree of ERS can activate the protective adaptation of cells, whereas sustained severe ERS triggers an apoptotic signal and leads to apoptosis. Acute pancreatitis is a disease caused by trypsin digestion of the pancreas, although the pathogenesis is not completely understood. However, a close association has been suggested between pancreatitis and ERS. This article reviewed relevant research advances and discussed the effect of ERS on the development and progression of acute pancreatitis.

Toxicological effects of benzo(a)pyrene, DDT and their mixture on the green mussel Perna viridis revealed by proteomic and metabolomic approaches

Benzo(a)pyrene (BaP) and dichlorodiphenyltrichloroethane (DDT) are persistent organic pollutants and environmental estrogens (EEs) with known toxicity towards the green mussel, Perna viridis. In this study, the toxic effects of BaP (10 µg/L) and DDT (10 µg/L) and their mixture were assessed in green mussel gills with proteomic and metabolomic approaches. Metabolic responses indicated that BaP mainly caused disturbance in osmotic regulation by significantly decrease in branched chain amino acids, dimethylamine and dimethylglycine in gills of male green mussels after exposure for 7 days. DDT mainly caused disturbance in osmotic regulation and energy metabolism by differential alteration of betaine, dimethylamine, dimethylglycine, amino acids, and succinate in gills of male green mussels. However, the mixture of BaP and DDT didn't show obvious metabolite changes. Proteomic analysis showed different protein expression profiles between different treatment groups, which demonstrated that BaP, DDT and their mixture may have different modes of action. Proteomic responses revealed that BaP induced cell apoptosis, disturbance in protein digestion and energy metabolism in gills of green mussels, whereas DDT exposure altered proteins that were associated with oxidative stress, cytoskeleton and cell structure, protein digestion and energy metabolism. However, the mixture of BaP and DDT affected proteins related to the oxidative stress, cytoskeleton and cell structure, protein biosynthesis and modification, energy metabolism, growth and apoptosis.

PRSS1 mutations and the proteinase/antiproteinase imbalance in the pathogenesis of pancreatic cancer

This study aimed to investigate the mutations in the serine protease 1 gene (PRSS1) and the imbalance between trypsin and α1-antitrypsin in patients with pancreatic cancer. Polymerase chain reaction (PCR) was performed to amplify the sequences of PRSS1 from 65 patients with pancreatic cancer and 260 healthy controls, direct sequencing was performed, and the clinical features were analyzed. In addition, enzyme-linked immunosorbent assay (ELISA) was employed to detect serum trypsin and α1-antitrypsin in pancreatic cancer patients and healthy controls in the same period. Mutations were found at the promoter and exon 3 of the PRSS1 in patients with pancreatic cancer. That is, five patients had c.410 C > T mutation causing p.Thr 137 Met, and three patients had c. -338 T > G mutation at the promoter of the PRSS1. In patients with PRSS1 mutations, serum trypsin was 34.5 ± 18.3 ng/mL, which was significantly higher than that in normal controls (10.65 ± 6.03 ng/mL) and other pancreatic cancer (28.61 ± 8.96 ng/mL). What is more, in pancreatic cancer patients, serum α1-antitrypsin was 1.69 ± 0.86 g/L, which was comparable to that in normal controls (1.55 ± 0.53 g/L), while the ratio of serum trypsin to α1-antitrypsin was 1.46-fold to normal controls. The results presented here have provided a greater insight into the PRSS1 mutations and proteinase-inhibitor interactions occurring in pancreatic cancer.

The Physiology and Pathophysiology of Pancreatic Ductal Secretion: The Background for Clinicians

The human exocrine pancreas consists of 2 main cell types: acinar and ductal cells. These exocrine cells interact closely to contribute to the secretion of pancreatic juice. The most important ion in terms of the pancreatic ductal secretion is HCO3. In fact, duct cells produce an alkaline fluid that may contain up to 140 mM NaHCO3, which is essential for normal digestion. This article provides an overview of the basics of pancreatic ductal physiology and pathophysiology. In the first part of the article, we discuss the ductal electrolyte and fluid transporters and their regulation. The central role of cystic fibrosis transmembrane conductance regulator (CFTR) is highlighted, which is much more than just a Cl channel. We also review the role of pancreatic ducts in severe debilitating diseases such as cystic fibrosis (caused by various genetic defects of cftr), pancreatitis, and diabetes mellitus. Stimulation of ductal secretion in cystic fibrosis and pancreatitis may have beneficial effects in their treatment.

Induction of chronic pancreatitis by pancreatic duct ligation activates BMP2, apelin, and PTHrP expression in mice

Chronic pancreatitis (CP) is a devastating disease with no treatments. Experimental models have been developed to reproduce the parenchyma and inflammatory responses typical of human CP. For the present study, one objective was to assess and compare the effects of pancreatic duct ligation (PDL) to those of repetitive cerulein (Cer)-induced CP in mice on pancreatic production of bone morphogenetic protein-2 (BMP2), apelin, and parathyroid hormone-related protein (PTHrP). A second objective was to determine the extent of cross talk among pancreatic BMP2, apelin, and PTHrP signaling systems. We focused on BMP2, apelin, and PTHrP since these factors regulate the inflammation-fibrosis cascade during pancreatitis. Findings showed that PDL- and Cer-induced CP resulted in significant elevations in expression and peptide/protein levels of pancreatic BMP2, apelin, and PTHrP. In vivo mouse and in vitro pancreatic cell culture experiments demonstrated that BMP2 stimulated pancreatic apelin expression whereas apelin expression was inhibited by PTHrP exposure. Apelin or BMP2 exposure inhibited PTHrP expression, and PTHrP stimulated upregulation of gremlin, an endogenous inhibitor of BMP2 activity. Transforming growth factor-β (TGF-β) stimulated PTHrP expression. Together, findings demonstrated that PDL- and Cer-induced CP resulted in increased production of the pancreatic BMP2, apelin, and PTHrP signaling systems and that significant cross talk occurred among pancreatic BMP2, apelin, and PTHrP. These results together with previous findings imply that these factors interact via a pancreatic network to regulate the inflammation-fibrosis cascade during CP. More importantly, this network communicated with TGF-β, a key effector of pancreatic pathophysiology. This novel network may be amenable to pharmacologic manipulations during CP in humans.

Cystic fibrosis-style changes in the early phase of pancreatitis

The early phase of both acute and chronic pancreatitis can be characterized by disrupt level and function of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel, decreased bicarbonate secretion, intraductal acidosis, decrease of fluid secretion and elevation of mucoprotein levels. It is almost needless to say that these intrapancreatic changes are very similar to the pathophysiological changes observed in cystic fibrosis. The aim of this mini review is to describe the development of the above mentioned pathological observations in details, moreover highlight some future therapeutic opportunities in pancreatitis.

Autoactivation of pancreatic trypsinogen is controlled by carbohydrate-specific interaction

Activation of bovine pancreatic trypsinogen (BPTG) by trypsin (BPT) was found to be inhibited by d GalN/GalNAc at pH 5.5, the pH of secretory granules in the pancreas. Binding studies with biotinylated sugar-polymers indicated that BPTG and BPT bind to α-GalNAc, α-Man, and α-Gal better at pH 5.5 than at pH 7.5. Ultraviolet-difference spectra indicated that BPTG binding to α-GalNAc differs substantially from BPTG binding to other sugars. The N-α-benzoyl-d,l-arginine-p-nitroanilide hydrochloride-hydrolyzing activity of BPT was only slightly affected by these sugars. The results indicate that the binding of GalNAc - containing glycoconjugates protects BPTG from autoactivation, and this may be a self-defense mechanism against intrapancreatic activation.

Pharmacological attenuation of chronic alcoholic pancreatitis induced hypersensitivity in rats

AIM

To characterize an alcohol and high fat diet induced chronic pancreatitis rat model that mimics poor human dietary choices.

METHODS

Experimental rats were fed a modified Lieber-DeCarli alcohol (6%) and high-fat (65%) diet (AHF) for 10 wk while control animals received a regular rodent chow diet. Weekly behavioral tests determined mechanical and heat sensitivity. In week 10 a fasting glucose tolerance test was performed, measuring blood glucose levels before and after a 2 g/kg bodyweight intraperitoneal (i.p.) injection of glucose. Post mortem histological analysis was performed by staining pancreas and liver tissue sections with hematoxylin and eosin. Pancreas sections were also stained with Sirius red and fast green to quantify collagen content. Insulin-expressing cells were identified immunohistochemically in separate sections. Tissue staining density was quantified using Image J software. After mechanical and heat sensitivity became stable (weeks 6-10) in the AHF-fed animals, three different drugs were tested for their efficacy in attenuating pancreatitis associated hypersensitivity: a Group II metabotropic glutamate receptor specific agonist (2R,4R)-4-Aminopyrrolidine-2,4-dicarboxylate (APDC, 3 mg/kg, ip; Tocris, Bristol, United Kingdom), nociceptin (20, 60, 200 nmol/kg, ip; Tocris), and morphine sulfate (3 mg/kg, μ-opioid receptor agonist; Baxter Healthcare, Deerfield, IL, United States).

RESULTS

Histological analysis of pancreas and liver determined that unlike control rats, AHF fed animals had pancreatic fibrosis, acinar and beta cell atrophy, with steatosis in both organs. Fat vacuolization was significantly increased in AHF fed rats (6.4% ± 1.1% in controls vs 23.8% ± 4.2%, P < 0.05). Rats fed the AHF diet had reduced fasting glucose tolerance in week 10 when peak blood glucose levels reached significantly higher concentrations than controls (127.4 ± 9.2 mg/dL in controls vs 161.0 ± 8.6 mg/dL, P < 0.05). This concurred with a 3.5 fold higher incidence of single and small 2-10 cell insulin-positive cell clusters (P < 0.05). Insulin expressing islet of Langerhans cells appeared hypertrophied while islet number and area measurements were not different from controls. Weekly behavioral tests determined that mechanical and heat sensitivities were significantly increased by 4 wk on AHF diet compared to controls. Hypersensitivity was attenuated with efficacy similar to morphine with single dose treatment of either metabotropic glutamate receptor 2/3 agonist APDC, or nociceptin, the endogenous ligand for opioid-receptor-like 1 receptor.

CONCLUSION

The AHF diet induces a chronic alcoholic pancreatitis in rats with measurable features resembling clinical patients with chronic pancreatitis and type 3c diabetes mellitus.

The apoptosis of peripheral blood lymphocytes promoted by hyperbaric oxygen treatment contributes to attenuate the severity of early stage acute pancreatitis in rats

The aim of this study was to investigate the immunoregulatory effects of hyperbaric oxygen (HBO) via promoting the apoptosis of peripheral blood lymphocytes (PBLs) to attenuate the severity of early stage acute pancreatitis (AP) in rats. Additionally, the persistence of the HBO treatment effects was evaluated. One hundred and twenty male Wistar rats were randomized into four groups: sham, AP, AP + normobaric oxygen (NBO), and AP + HBO. Each group consisted of 30 rats. Four hours after the induction of AP, the 30 rats in the AP + NBO group were given normobaric oxygen treatment with 100 % oxygen at 1 atm for 90 min. The 30 rats in the AP + HBO group received 100 % oxygen at 2.5 atm for 90 min, with a compression/decompression time of 15 min. The 30 rats in the AP group remained untreated. At 6, 12, and 24 h after the induction of AP, surviving rats from each group were sacrificed, and the blood and tissue samples were collected for the following measurements: the partial pressure of oxygen (PaO2) and oxygen saturation (SaO2) of the arterial blood, the levels of serum amylase, lipase, interleukin-2 (IL-2), interferon-γ (IFN-γ), interleukin-10 (IL-10), hepatocyte growth factor (HGF), and reactive oxygen species (ROS), and the mitochondrial membrane potential (∆Ψm) of the PBLs. The expression levels of procaspase-3, caspase-3, procaspase-9, and caspase-9 were also evaluated in the PBLs. Additionally, the apoptosis of PBLs was assessed, and the pancreatic tissues were subjected to a histopathological analysis by pathological grading and scoring. The histopathology of the lung, liver, kidney, duodenum, and heart was also analyzed at 12 h after the induction of AP. Significant differences were found at 6 and 12 h after AP induction. The HBO treatment significantly elevated the PaO2 and SaO2 levels, and the ROS levels in the PBLs. Additionally, HBO downregulated the levels of amylase and lipase. The HBO treatment also reduced the ∆Ψm levels, upregulated the expression of caspase-3 and caspase-9, and increased the apoptosis rate of the PBLs. Moreover, the HBO treatment decreased the serum concentrations of IL-2, IFN-γ and HGF, and reduced the pathological scores of the pancreatic tissue. The histopathological changes of the lung, liver, kidney, duodenum, and heart were also improved. A significant elevation of IL-10 occurred only at the 12-h time point. However, no obvious differences were found at the 24-h time point. This study demonstrated that the HBO treatment can promote the apoptosis of PBLs via a mitochondrial-dependent pathway and inhibit the inflammatory response. These immunoregulatory effects may play an important therapeutic role in attenuating the severity of early stage AP. The repeated administration of HBO or the use of HBO in combination with other approaches may further improve outcomes.

Flavocoxid, a nutraceutical approach to blunt inflammatory conditions

Flavonoids, from Scutellaria baicalensis (Chinese skullcap) and Acacia catechu (black catechu), have been shown to exert a variety of therapeutic effects, including anti-inflammatory, antiviral, antibacterial, and anticancer activities. Flavocoxid is a mixed extract containing baicalin and catechin and it acts as a dual balanced inhibitor of cyclooxygenase-1 (COX-1) and COX-2 peroxidase enzyme activities with a significant inhibition of 5-lipoxygenase (5-LOX) enzyme activity in vitro. Flavocoxid downregulates gene or protein expression of several inflammatory markers and exerts also strong antioxidant activity in several experimental models. Controlled clinical trials and a postmarketing study have clearly shown that flavocoxid is as effective as naproxen in managing the signs and symptoms of osteoarthritis of the knee and it has better upper gastrointestinal, renal, and respiratory safety profile than naproxen. Flavocoxid may therefore provide a potential therapeutic approach to the treatment of chronic inflammatory conditions.

Differential regulation of pancreatic digestive enzymes during chronic high-fat diet-induced obesity in C57BL/6J mice

Exocrine pancreatic digestive enzymes are essential for the digestion of dietary components and are regulated by them. Chronic excess dietary high fat (HF) consumption is a contributing factor of diet-induced obesity (DIO) and associated chronic diseases and requires adaptation by the pancreas. The aim of the present study was to investigate the effects of chronic HF diet feeding on exocrine pancreatic digestive enzyme transcript levels in DIO C57BL/6J mice. C57BL/6J mice were fed diets containing either 10 or 45% energy (E%) derived from fat for 12 weeks (n 10 mice per diet group). Pancreatic tissue and blood samples were collected at 0, 4 and 12 weeks. The expression of a panel of exocrine pancreatic digestive enzymes was analysed using quantitative RT-PCR and Western blot analysis. The HF (45 E%) diet-fed C57BL/6J mice developed obesity, hyperleptinaemia, hyperglycaemia and hyperinsulinaemia. The transcript levels of pancreatic lipase (PL), pancreatic lipase-related protein 2 (PLRP2) and pancreatic phospholipase A2 (PLA2) were initially elevated; however, they were down-regulated to basal control levels at week 12. The transcript levels of colipase were significantly affected by diet and time. The protein levels of PL and PLRP2 responded to HF diet feeding. The transcript levels of amylase and proteases were not significantly affected by diet and time. The transcript levels of specific lipases in hyperinsulinaemic, hyperleptinaemic and hyperglycaemic DIO C57BL/6J mice are down-regulated. However, these mice compensate for this by the post-transcriptional regulation of the levels of proteins that respond to dietary fat. This suggests a complex regulatory mechanism involved in the modulation of fat digestion.

Mesenteric lymph drainage alleviates acute kidney injury induced by hemorrhagic shock without resuscitation

This study aimed to investigate the effect of mesenteric lymph drainage on the acute kidney injury induced by hemorrhagic shock without resuscitation. Eighteen male Wistar rats were randomly divided into sham, shock, and drainage groups. The hemorrhagic shock model (40 mmHg, 3 h) was established in shock and drainage groups; mesenteric lymph drainage was performed from 1 h to 3 h of hypotension in the drainage group. The results showed that renal tissue damage occurred; the levels of urea, creatinine, and trypsin in the plasma as well as intercellular adhesion molecule-1 (ICAM-1), receptor of advanced glycation end-products (RAGE), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), lactic acid (LA), and 2,3-DPG in the renal tissue were increased in the shock group after 3 h of hypotension. Mesenteric lymph drainage lessened the following: renal tissue damage; urea and trypsin concentrations in the plasma; ICAM-1, RAGE, TNF-α, MDA, and LA levels in the renal tissue. By contrast, mesenteric lymph drainage increased the 2,3-DPG level in the renal tissue. These findings indicated that mesenteric lymph drainage could relieve kidney injury caused by sustained hypotension, and its mechanisms involve the decrease in trypsin activity, suppression of inflammation, alleviation of free radical injury, and improvement of energy metabolism.

Pancreatitis activates pancreatic apelin-APJ axis in mice

Pancreatitis is classified into acute pancreatitis (AP) and chronic pancreatitis (CP). Apelin, a small regulatory peptide, is the endogenous ligand for the APJ receptor. Apelin and APJ are expressed in the pancreas. The aims of this study were to examine whether apelin influences the inflammatory and fibrosis responses to pancreatitis in mice and to identify mechanisms behind apelin's activities. Supramaximal cerulein induction of AP or CP caused significant (P < 0.05) elevations in pancreatic apelin and APJ expression. Levels declined during the recovery phases. In apelin gene-knockout mice with pancreatitis, pancreatic neutrophil invasion and myeloperoxidase activity were enhanced significantly, and apelin treatment suppressed both. Apelin exposure reduced CP-induced elevations of extracellular matrix-associated proteins. Apelin inhibited PDGF-simulated connective tissue growth factor production and proliferation of pancreatic stellate cells (PSCs). Serum granulocyte colony-stimulating factor and keratinocyte cytokine levels were higher in apelin gene-knockout than wild-type mice with pancreatitis. Apelin reduced AP- and CP-induced elevations in pancreatic NF-κB activation. Together, these findings imply that the pancreatic apelin-APJ system functions to curb the inflammatory and fibrosis responses during pancreatitis. Furthermore, findings suggest that apelin reduces inflammation and fibrosis by reducing neutrophil recruitment and PSC activity. Inhibition of neutrophil invasion may be mediated by reduced keratinocyte cytokine and granulocyte colony-stimulating factor secretion. Apelin-induced reductions in PSC proliferation and connective tissue growth factor production are putative mechanisms underlying apelin's inhibition of extracellular matrix production. The apelin-associated changes in NF-κB binding may be linked to apelin's regulation of pancreatic inflammatory and fibrosis responses during pancreatitis.

Differentially expressed kinase genes associated with trypsinogen activation in rat pancreatic acinar cells treated with taurolithocholic acid 3-sulfate

Trypsinogen activation is the initial factor involved in the development of all types of acute pancreatitis (AP) and has been suggested to be regulated by protein kinases. In the present study, AR42J rat pancreatic acinar cells were treated with taurolithocholic acid 3-sulfate (TLC-S), and trypsinogen activation was detected with bis-(CBZ-L-isoleucyl-L-prolyl-L-arginine amide) dihydrochloride (BZiPAR) staining and flow cytometry. Differentially expressed protein kinase genes were screened by Gene Chip analysis, and the functions of these kinases were analyzed. A significantly increased activation of trypsinogen in AR42J cells following treatment with TLC-S was observed. A total of 22 differentially expressed protein kinase genes were found in the TLC-S group, among which 19 genes were upregulated and 3 were downregulated. Based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, kinase genes of the same KEGG pathways were connected to create a network through signaling pathways, and 10 nodes of kinases were identified, which were mitogen-activated protein kinase (Mapk)8, Mapk14, Map2k4, interleukin-1 receptor-associated kinase 3 (Irak3), ribosomal protein S6 kinase, 90 kDa, polypeptide 2 (Rps6ka2), protein kinase C, alpha (Prkca), v-yes-1 Yamaguchi sarcoma viral related oncogene homolog (Lyn), protein tyrosine kinase 2 beta (Ptk2b), p21 protein (Cdc42/Rac)-activated kinase 4 (Pak4) and FYN oncogene related to SRC, FGR, YES (Fyn). The interactions between signaling pathways were further analyzed and a network was created. MAPK and calcium signaling pathways were found to be located at the center of the network. Thus, protein kinases constitute potential drug targets for AP treatment.

Alcohol consumption on pancreatic diseases

Although the association between alcohol and pancreatic diseases has been recognized for a long time, the impact of alcohol consumption on pancreatitis and pancreatic cancer (PC) remains poorly defined. Nowadays there is not consensus about the epidemiology and the beverage type, dose and duration of alcohol consumption causing these diseases. The objective of this study was to review the epidemiology described in the literature for pancreatic diseases as a consequence of alcoholic behavior trying to understand the association between dose, type and frequency of alcohol consumption and risk of pancreatitis and PC. The majority of the studies conclude that high alcohol intake was associated with a higher risk of pancreatitis (around 2.5%-3% between heavy drinkers and 1.3% between non drinkers). About 70% of pancreatitis are due to chronic heavy alcohol consumption. Although this incidence rate differs between countries, it is clear that the risk of developing pancreatitis increases with increasing doses of alcohol and the average of alcohol consumption vary since 80 to 150 g/d for 10-15 years. With regard to PC, the role of alcohol consumption remains less clear, and low to moderate alcohol consumption do not appear to be associated with PC risk, and only chronic heavy drinking increase the risk compared with lightly drinkers. In a population of 10%-15% of heavy drinkers, 2%-5% of all PC cases could be attributed to alcohol consumption. However, as only a minority (less than 10% for pancreatitis and 5% for PC) of heavily drinkers develops these pancreatic diseases, there are other predisposing factors besides alcohol involved. Genetic variability and environmental exposures such as smoking and diet modify the risk and should be considered for further investigations.

Zymophagy: selective autophagy of secretory granules

Timing is everything. That's especially true when it comes to the activation of enzymes created by the pancreas to break down food. Pancreatic enzymes are packed in secretory granules as precursor molecules called zymogens. In physiological conditions, those zymogens are activated only when they reach the gut, where they get to work releasing and distributing nutrients that we need to survive. If this process fails and the enzymes are prematurely activated within the pancreatic cell, before they are released from the gland, they break down the pancreas itself causing acute pancreatitis. This is a painful disease that ranges from a mild and autolimited process to a severe and lethal condition. Recently, we demonstrated that the pancreatic acinar cell is able to switch on a refined mechanism that could explain the autolimited form of the disease. This is a novel selective form of autophagy named zymophagy, a cellular process to specifically detect and degrade secretory granules containing activated enzymes before they can digest the organ. In this work, we revise the molecules and mechanisms that mediate zymophagy, a selective autophagy of secretory granules.

Genetics of pancreatitis: an update for clinicians and genetic counselors

With novel genetic technologies available, there is a paradigm shift in the way that risk assessments, diagnoses,and therapies for genetic susceptibility syndromes are addressed. Hereditary pancreatitis is among these conditions, for which genetic counseling and next generation sequencing, help families better understand, cope with and live healthier lives. Identifying a genetic etiology to a condition formally believed to be solely environmentally induced can alter the path for treatment for many patients. This finding introduces the concept of gene-environment interactions in human disease and the relationship between genetic predisposition and exposure risk in disease development. The genetic counseling process is complex with medical explanations, psychosocial issues relating to coping with diagnosis, potential future health problems, recurrence risks and family planning. These sometimes difficult conversations can be facilitated by a genetic counselor as a member of the multidisciplinary team. This chapter addresses the intricate medical and psychosocial issues that can arise in the setting of treating patients with hereditary pancreatitis.

Trypsin reduces pancreatic ductal bicarbonate secretion by inhibiting CFTR Cl⁻ channels and luminal anion exchangers

BACKGROUND & AIMS

The effects of trypsin on pancreatic ductal epithelial cells (PDECs) vary among species and depend on the localization of proteinase-activated receptor 2 (PAR-2). We compared PAR-2 localization in human and guinea-pig PDECs, and used isolated guinea pig ducts to study the effects of trypsin and a PAR-2 agonist on bicarbonate secretion.

METHODS

PAR-2 localization was analyzed by immunohistochemistry in guinea pig and human pancreatic tissue samples (from 15 patients with chronic pancreatitis and 15 without pancreatic disease). Functionally, guinea pig PDECs were studied by microperfusion of isolated ducts, measurements of intracellular pH and intracellular Ca(2+) concentration, and patch clamp analysis. The effect of pH on trypsinogen autoactivation was assessed using recombinant human cationic trypsinogen.

RESULTS

PAR-2 localized to the apical membrane of human and guinea pig PDECs. Trypsin increased intracellular Ca(2+) concentration and intracellular pH and inhibited secretion of bicarbonate by the luminal anion exchanger and the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel. Autoactivation of human cationic trypsinogen accelerated when the pH was reduced from 8.5 to 6.0. PAR-2 expression was strongly down-regulated, at transcriptional and protein levels, in the ducts of patients with chronic pancreatitis, consistent with increased activity of intraductal trypsin. Importantly, in PAR-2 knockout mice, the effects of trypsin were markedly reduced.

CONCLUSIONS

Trypsin reduces pancreatic ductal bicarbonate secretion via PAR-2-dependent inhibition of the apical anion exchanger and the CFTR Cl(-) channel. This could contribute to the development of chronic pancreatitis by decreasing luminal pH and promoting premature activation of trypsinogen in the pancreatic ducts.